Security device for monitoring integrity of closed objects

Abstract

A security device ( 20 ) is a compact and inexpensive device for monitoring the integrity of closed objects that indicates when the state of a monitored condition inside the closed object has changed. The device ( 20 ) is small-sized so that it can also be placed inside small closed objects, e.g. a briefcase, box, envelope or alike, and that it is inconspicuous to the observer if the closed object is opened. The device ( 20 ) is relocatable inside the closed object. The device ( 20 ) comprises a controller ( 4 ) and associated memory ( 8 ), a time counter ( 6 ) in connection with the controller ( 4 ), sensors ( 2 ) communicating with the controller ( 4 ) and arranged to sense changes in conditions inside the closed object and indicating means ( 12 ) communicating with the controller ( 4 ) and arranged to wirelessly indicate invasion against the integrity of the closed object. While the changes in conditions inside the closed object comply with certain predefined conditions the alarm indication can be blocked. The alarm indication of the security device ( 20 ) can also be activated and deactivated externally by means of a remote control or automatically.

1. A security device for monitoring changes in conditions of a closed object, the device comprising
 at least one sensor arranged to sense changes in conditions of the closed object in successive time points and arranged to produce an alarm signal upon occurrence of such detected changes exceeding a specified limit value, 
 an indication unit communicating with the sensor, said indication unit comprising at least a transmitter arranged to indicate outside the closed object a presence of said alarm signal by transmitting said alarm signal, wherein 
 said at least one sensor is arranged to switch off said indication unit before indicating the presence of said alarm signal if the changes detected comply with a certain reference condition. 
 
     
     
       2. The device according to  claim 1 , wherein the device further comprises a comparing module arranged to compare sensed conditions between successive time points in order to produce the change detected and to compare the change detected with the reference condition. 
     
     
       3. The device according to  claim 2 , wherein the reference condition is specified to be within a predefined limit value. 
     
     
       4. The device according to  claim 1 , wherein the device further comprises a comparing module arranged to compare sensed conditions in successive time points with the reference condition. 
     
     
       5. The device according to  claim 4 , wherein the reference condition is specified not to be within a predefined limit value. 
     
     
       6. The device according to  claim 1 , wherein the device further comprises a memory arranged to store the sensed condition in successive time points. 
     
     
       7. The device according to  claim 6 , wherein the memory is arranged to store the reference conditions. 
     
     
       8. The device according to  claim 1 , wherein the device further comprises a counter arranged to generate a time signal and a certain time interval between successive time points. 
     
     
       9. The device according to  claim 1 , wherein the indication unit further comprises an input arranged to receive an external command and arranged to activate and deactivate said indicating means in accordance with the external command. 
     
     
       10. The device according to  claim 9 , wherein the input comprises at least a wireless receiver arranged to receive the external command from an external wireless transmitter and arranged to be activated/deactivated according to said external command. 
     
     
       11. The device according to  claim 9 , wherein an external radio frequency identification transmitter or a coloured cellular transmitter is arranged to generate the external command to a specified area. 
     
     
       12. The device according to  claim 9 , wherein said wireless transmitter is arranged to operate in at least two different frequency bands. 
     
     
       13. The device according to  claim 1 , wherein the indication unit comprises a wireless positioning transmitter arranged to transmit a position information indicating position of producing the alarm signal and/or indicating a position of the security device. 
     
     
       14. The device according to  claim 1 , wherein the sensor comprises at least one of the following sensors: light sensor, temperature sensor, pressure sensor, motion sensor, humidity sensor and accelerator. 
     
     
       15. A security device for monitoring changes in conditions of a closed object, the device comprising
 means for sensing changes in conditions of the closed object in successive time points and arranged to produce an alarm signal upon occurrence of such detected changes exceeding a specified limit value, 
 means, communicating with the means for sensing, for indicating outside the closed object a presence of said alarm signal by transmitting said alarm signal, wherein 
 said means for sensing is arranged to switch off said means for selecting before indicating the presence of said alarm signal if the changes detected comply with a certain reference condition. 
 
     
     
       16. The device according to  claim 15 , further comprising means for comparing sensed conditions between successive time points in order to produce the change detected and to compare the change detected with the reference condition. 
     
     
       17. The device according to  claim 16 , wherein the reference condition is specified to be within a predefined limit value.